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Staging: s5k3e2fx.c: simplify complexity by factoring

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the code was looping, setting s_move[i] to the following calculations

if (actual_step>= 0)
         s_move[i] = ((((i + 1) * gain + 0x200) - (i * gain + 0x200)) / 0x400);
else
         s_move[i] = ((((i + 1) * gain - 0x200) - (i * gain - 0x200)) / 0x400);

but, this code reduces to the expression
	s_move[i] = gain>>  10;

The reason for the complexity was to generate a step function with
integer division and rounding to land on specific values. But these calculations
can be simplified to the following code:

	gain = ((actual_step<<  10) / 5)>>  10;
	for (i = 0; i<= 4; i++)
		s_move[i] = gain;

Signed-off-by: Justin Madru<jdm64@gawab.com>
Reviewed-by: Ray Lee<ray-lk@madrabbit.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Justin Madru
2009-12-18 15:52:53 -08:00
committed by Greg Kroah-Hartman
parent 096417e087
commit 8c172dde41
1 changed files with 3 additions and 7 deletions
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10
drivers/staging/dream/camera/s5k3e2fx.c
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@@ -1093,14 +1093,10 @@ static int32_t s5k3e2fx_move_focus(int direction, int32_t num_steps)
actual_step = step_direction * (int16_t)num_steps;
pos_offset = init_code + s5k3e2fx_ctrl->curr_lens_pos;
gain = actual_step * 0x400 / 5;
gain = ((actual_step << 10) / 5) >> 10;
for (i = 0; i <= 4; i++) {
if (actual_step >= 0)
s_move[i] = ((((i+1)*gain+0x200) - (i*gain+0x200))/0x400);
else
s_move[i] = ((((i+1)*gain-0x200) - (i*gain-0x200))/0x400);
}
for (i = 0; i <= 4; i++)
s_move[i] = gain;
/* Ring Damping Code */
for (i = 0; i <= 4; i++) {